JP5997352B2 - V-ribbed belt - Google Patents

Description

  The present invention relates to a V-ribbed belt used for driving an automobile engine accessory, and more particularly to a V-ribbed belt that can reduce the torque loss (fuel consumption) of the engine by reducing the bending loss of the V-ribbed belt.

  A power transmission belt used for driving an auxiliary machine such as an automobile engine has changed from a low edge belt (V belt) to a V ribbed belt. In particular, a V-ribbed belt made of a rubber composition mainly composed of an ethylene / α-olefin elastomer (for example, EPDM) has good durability (heat resistance and cold resistance) with respect to chloroprene rubber (CR) and contains halogen. It has become mainstream because it is not. And since durability was sufficiently ensured by using EPDM, since then, development has been mainly carried out for the purpose of improving sound resistance (especially sound generation during water injection) (for example, patent documents). 1).

  By the way, in recent years, in addition to durability and soundproofing, a belt transmission system using a V-ribbed belt, for example, an automotive engine accessory drive system, suppresses the torque cross of the V-ribbed belt between the drive shaft and the driven shaft. There is a request to reduce fuel consumption. In particular, light vehicles and small vehicles with small displacements have severe restrictions on mass, space, and cost, and there are limited items for improving fuel consumption, so there is a strong demand for reducing fuel consumption in this type of vehicle.

  For the purpose of reducing fuel consumption, for example, Patent Document 2 discloses that the thickness of the belt is reduced, ethylene-2,6-naphthalate is used for the core wire, and the tensile elastic modulus of the belt is 14,000 to 17, A 000 N / rib V-ribbed belt is disclosed. According to this, it becomes possible to reduce the thickness of the belt without lowering the elastic modulus of the belt, and by reducing the thickness, the bending fatigue resistance of the belt is improved, and the torque loss is reduced to reduce the fuel consumption of the engine. It is described that it can.

  In Patent Document 3, the rubber composition forming the compression layer is mainly composed of an ethylene / α-olefin elastomer, and the compression layer has an initial strain of 0.1%, a frequency of 10 Hz, and a strain of 0.5%. Discloses a V-ribbed belt having a tan δ (loss tangent) at 40 ° C. of less than 0.150 when measuring dynamic viscoelasticity. According to this document, it is described that the torque loss can be reduced by reducing the internal loss (self-heating) of the compression rubber layer when the belt is driven.

JP 2007-232205 A Japanese Patent Laid-Open No. 11-6547 JP 2010-276127 A

  Certainly, as a means of reducing torcross at the time of running the belt, the internal loss is reduced by reducing the belt thickness as in Patent Document 2 or decreasing the tan δ of the compressed rubber layer as in Patent Document 3. Is valid.

  However, the torque loss cannot be sufficiently reduced only by these means. In other words, since the belt bends around the core wire, if the position of the core wire (position in the belt thickness direction) embedded between the stretch layer and the compression layer is on the belt outer periphery (back surface) side, the belt The bending stress of the core wire when wound is increased, the bending loss is increased, and the torque cross is increased. In addition, the thickness of the compression layer and the size of the rib forming the compression layer (related to rib height and rib pitch) are also factors that affect the torcross, and if this is large, the stress required to bend the compression layer Even if the (compressive stress) is high or the tan δ of the rubber composition forming the compression layer is the same, the internal loss due to the compressive deformation increases and the torque loss increases. Furthermore, the belt width is also important. If this width is large, the belt bending loss increases and the torque loss tends to increase.

  Specifically, in the V-ribbed belt of Patent Document 2, the rib pitch is 3.56 mm, the rib height is 2.9 mm (see paragraph [0032]), and the rib shape is increased. Could not be reduced sufficiently. Further, in the V-ribbed belt of Patent Document 3, although tan δ of the rubber composition forming the compression layer is reduced to reduce torcross, it is not sufficient by itself.

  Accordingly, an object of the present invention is to provide a V-ribbed belt capable of reducing the torque loss of the engine by reducing the belt bending loss and maintaining the transmission performance of the belt.

  A first invention for solving the above problems is a V-ribbed belt that is used by being wound between pulleys, and is provided on a stretch layer that forms a back surface of the V-ribbed belt, and on one surface of the stretch layer, A compression layer having a plurality of ribs extending parallel to each other along the longitudinal direction of the V-ribbed belt; and a core wire embedded along the longitudinal direction of the V-ribbed belt between the stretch layer and the compression layer. The distance from the outer peripheral part on the rib side of the core wire to the tip of the rib is 2.0 to 2.6 mm, and the distance from the outer peripheral part on the rib side of the core wire to the bottom of the rib is It is 0.3 to 1.2 mm.

  According to said structure, the thickness of a compression layer is set by setting the distance from the outer peripheral part (henceforth a core wire bottom part) of the rib side of a core wire to the front-end | tip part of a rib in the range of 2.0-2.6 mm. , The stress of the compression layer (compression stress) and the internal loss when the V-ribbed belt is wound between the pulleys can be reduced, and the torque loss can be reduced. Also, by setting the distance from the bottom of the core wire to the bottom of the rib in the range of 0.3 to 1.2 mm, the bending stress of the core wire when the V-ribbed belt is wound between the pulleys is reduced (the bending loss is reduced). Less) and torcross can be reduced.

  In the first invention, the rib width (rib pitch) is 2.0 to 3.0 mm, and the distance (rib height) from the bottom of the rib to the tip of the rib is 1.1 to 1. It is characterized by being 8 mm.

  According to the above configuration, the compression layer is formed by setting the rib width (rib pitch) and the distance from the bottom of the rib to the tip of the rib (rib height) in a range smaller than the conventional (Patent Document 2). The rib shape to be reduced can be reduced, and the torcross can be reduced by reducing the internal loss due to the compression deformation of the rib and the compression stress of the rib.

  The first invention is characterized in that the stretch layer is formed of a rubber composition.

  According to said structure, it becomes easy to extend compared with the conventionally used canvas by forming a stretch layer with a rubber composition, and the tensile stress of a stretch layer when a V-ribbed belt is wound around a pulley can be reduced. This can reduce the bending loss of the V-ribbed belt and reduce the torque cross.

  Moreover, 1st invention is characterized by the distance from the center of the said core wire to a V-ribbed belt back surface being 0.6-1.5 mm.

  Like the said structure, by making the distance from the center of a core wire into a V ribbed belt back surface into the range of 0.6-1.5 mm, the tensile stress of an extension layer can be made small and a torcloth can be reduced.

  In the second invention, in the V-ribbed belt, the width of the rib is 2.34 mm, and the distance from the outer peripheral portion on the rib side of the core wire to the tip portion of the rib is 2.3 to 2 .6 mm, and the distance from the outer peripheral portion on the rib side of the core wire to the bottom of the rib is 0.8 to 1.1 mm.

  According to a third aspect of the present invention, in the V-ribbed belt according to any one of the first to third aspects, the core wire has a diameter of 0.6 to 1.25 mm.

  As in the above configuration, when the diameter of the core wire is in the range of 0.6 to 1.25 mm, the bending stress of the core wire itself becomes too large while maintaining the strength and tensile stress of the V-ribbed belt itself. It is possible to prevent an increase in toll cloth due to.

  In the V-ribbed belt according to any one of the first to third aspects, the edge of the tip of the rib may have a square shape.

  According to said structure, since the edge of the front-end | tip part of a rib is made into square shape, the area which a rib and the groove | channel of a pulley contact can be enlarged, and transmission performance can be maintained.

  It is possible to provide a V-ribbed belt capable of reducing the torque loss of the engine by reducing the bending loss of the belt and maintaining the transmission performance of the belt.

It is a schematic explanatory drawing of the V-ribbed belt which concerns on this embodiment. It is AA 'sectional drawing of the V-ribbed belt which concerns on this embodiment. It is a simplified sectional view of the width direction of the V ribbed belt concerning this embodiment. It is comparison explanatory drawing of the rib shape of the V-ribbed belt which concerns on this embodiment, and the rib shape of the conventional V-ribbed belt. It is explanatory drawing regarding the position of the core wire of the V-ribbed belt which concerns on this embodiment. It is explanatory drawing regarding the measuring method of the torque cross of the V-ribbed belt which concerns on an Example, and the measuring method of transmission performance. It is the figure which described the measurement result of the torque cross with respect to the belt tension of the V ribbed belt which concerns on an Example. It is sectional drawing of the V-ribbed belt which concerns on other embodiment. It is sectional drawing of the V-ribbed belt which concerns on other embodiment.

(Embodiment)
Hereinafter, embodiments of a V-ribbed belt according to the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the V-ribbed belt 1 according to the present embodiment is used by being wound between, for example, a drive pulley 2 and a driven pulley 3 in a power transmission system such as an engine accessory drive system.

(Configuration of V-ribbed belt 1)
As shown in FIG. 2, the V-ribbed belt 1 of the present embodiment is made of a rubber composition, and is provided on one surface of the stretch layer 11 that forms the back surface 1A of the V-ribbed belt, and in the longitudinal direction M of the V-ribbed belt M. A compression layer 12 having a plurality of ribs 13 extending in parallel to each other along the core, a core wire 14 embedded along the longitudinal direction M of the V-ribbed belt between the extension layer 11 and the compression layer 12, and the extension layer 11. An adhesive layer 15 is provided between the compression layer 12. Note that the adhesive layer 15 is not essential, and is provided for the purpose of improving the adhesiveness of the core wire 14, the stretch layer 11, and the compression layer 12, and the adhesive layer 15 and the stretch layer as in this embodiment. 11, the core wire 14 may be embedded in the adhesive layer 15, or the core wire 14 may be embedded between the compression layer 12 and the adhesive layer 15. May be.

  Also, the V-ribbed belt 1 shown in FIG. 2 is formed of a rubber composition containing a stretch layer 11, an adhesive layer 15 disposed below the stretch layer 11, and a short fiber 16 disposed below the stretch layer 11. The compression layer 12 is provided. In other words, in the V-ribbed belt 1, a rubber layer is constituted by three layers of an extension layer 11, an adhesive layer 15, and a compression layer 12, and the compression layer 12 constitutes an inner layer. Note that the adhesive layer 15 and the compression layer 12 may be defined as constituting an inner layer. Further, the core wire 14 is arranged so as to be embedded in the main body of the V-ribbed belt 1 along the longitudinal direction M of the V-ribbed belt, half of which is embedded in the stretch layer 11 and the other half is embedded in the adhesive layer 15. It is arranged in the state. The compressed layer 12 is provided with a plurality of ribs 13 having a substantially trapezoidal cross section in the V-ribbed belt width direction N and extending in the longitudinal direction M of the V-ribbed belt. Here, the short fibers 16 contained in the compressed layer 12 are contained in a state oriented in the V-ribbed belt width direction N, which is a direction orthogonal to the V-ribbed belt longitudinal direction M. Further, the surface of the rib 13 is a polished surface.

Next, in order to describe a specific shape and material of the V-ribbed belt 1, each part and dimensions of the V-ribbed belt 1 are described below with reference to a simplified cross-sectional view in the V-ribbed belt width direction N of the V-ribbed belt 1 in FIG. Define as follows. Here, the compressed layer 12 will be described as including the adhesive layer 15.
a: Distance from the center of the core [2] to the back of the V-ribbed belt [1], which corresponds to the thickness of the stretched layer 11.
b: Distance from the core bottom [3] corresponding to the outer peripheral portion of the core 14 on the rib 13 side to the V-ribbed belt back [1].
c: Distance from the rib bottom [4] to the back of the V-ribbed belt [1].
d: Distance from the rib tip [5] to the back of the V-ribbed belt [1], which corresponds to the thickness of the V-ribbed belt 1.
e: The width of the rib 13 in the V-ribbed belt width direction N, which corresponds to the rib pitch.
f: A product obtained by multiplying the rib pitch e by the number of ribs, and corresponds to the width of the V-ribbed belt 1.
g: The length of the inclined surface of the rib 13 from the rib bottom [4] to the rib tip [5].
h: Distance from the rib bottom [4] to the core bottom [3].
i: Distance from the rib tip [5] to the rib bottom [4], which corresponds to the height of the rib 13.
j: Distance from the core bottom [3] to the rib tip [5].
k: distance from the rib tip [5] to the center of the core [2], which corresponds to the thickness of the compression layer 12.

  In the V-ribbed belt 1 in the present embodiment, the distance j from the core bottom [3] to the rib tip [5] is in the range of 2.0 to 2.6 mm, and the core bottom [3] to the rib The distance h to the bottom [4] is in the range of 0.3 to 1.2 mm. According to this, the thickness of the compression layer 12 can be reduced by setting the distance j from the core bottom [3] to the rib tip [5] in the range of 2.0 to 2.6 mm, When the V-ribbed belt 1 is wound between the drive pulley 2 and the driven pulley 3, the stress (compression stress) and internal loss of the compression layer 12 can be reduced to reduce the torque loss. Further, the V-ribbed belt 1 is wound between the driving pulley 2 and the driven pulley 3 by setting the distance h from the core bottom [3] to the rib bottom [4] within a range of 0.3 to 1.2 mm. The torcross can be reduced by reducing the bending stress of the core wire 14 when hung (small bending loss).

  When the distance j from the core bottom [3] to the rib tip [5] is less than 2.0 mm, the compression layer 12 becomes excessively thin, and thus the lateral pressure resistance against the pressure from the driving pulley 2 and the driven pulley 3 is reduced. If the thickness exceeds 2.6 mm, the thickness of the compression layer 12 increases and the torcross of the V-ribbed belt 1 increases. In the above, the distance j from the core bottom [3] to the rib tip [5] is in the range of 2.0 to 2.6 mm, more preferably in the range of 2.3 to 2.6 mm. It is good.

  Further, if the distance h from the core bottom [3] to the rib bottom [4] is less than 0.3 mm, the core 14 is partially exposed from the rib bottom [4] during polishing, resulting in poor appearance. Since the layer of the rubber composition interposed between the core wire 14 and the rib bottom [4] becomes extremely thin, a vertical crack (in the thickness direction of the V-ribbed belt 1) is likely to occur at the bottom of the valley between the adjacent ribs 13. As a result, there is a risk of breaking along the longitudinal direction M of the V-ribbed belt. On the other hand, if it exceeds 1.2 mm, the bending stress of the core wire 14 when the V-ribbed belt 1 is wound around the drive pulley 2 and the driven pulley 3 becomes large, and the torque cross tends to increase. In addition, the distance h from the core bottom [3] to the rib bottom [4] is more preferably in the range of 0.4 to 1.1 mm.

  Further, in the V-ribbed belt 1 in the present embodiment, the rib width (rib pitch e) is in the range of 2.0 to 3.0 mm, and the distance (rib height) from the rib bottom [4] to the rib tip [5]. I) is in the range of 1.1 to 1.8 mm. According to this, by setting the rib width (rib pitch e) and the distance (rib height i) from the rib bottom [4] to the rib tip [5] in a range smaller than the conventional (Patent Document 2). The shape of the ribs 13 forming the compression layer 12 can be reduced, and the internal loss resulting from the compression deformation of the ribs 13 and the compression stress of the ribs 13 can be reduced to reduce the torque cross.

  As described in paragraph [0004] of Patent Document 2, the distance from the rib bottom [4] to the rib tip [5] (rib height i) is reduced. Although the contact area with the pulley 3 is reduced and the transmission efficiency is lowered, in this embodiment, the rib pitch e is reduced, so that the number of ribs per width of the V-ribbed belt 1 can be increased, thereby transmitting. Efficiency can be maintained. The value obtained by multiplying the rib pitch e and the number of ribs is the width f of the V-ribbed belt 1, but since the rib pitch e is reduced, the width f of the V-ribbed belt 1 can be reduced even if the number of ribs is increased. Torque loss can be reduced by reducing the bending loss of the belt without lowering the transmission efficiency.

  If the rib width (rib pitch e) is less than 2.0 mm, the side pressure resistance of the rib 13 against the pressure from the driving pulley 2 and the driven pulley 3 is insufficient. On the other hand, if the rib width exceeds 3.0 mm, the shape of the rib 13 is large. As a result, the stress and internal loss during compression deformation increase, and the torque loss cannot be sufficiently reduced. A preferable range of the rib pitch e is 2.2 to 2.8 mm.

  Further, when the distance (rib height i) from the rib bottom [4] to the rib tip [5] is less than 1.1 mm, the rib 13 and the grooves provided in the driving pulley 2 and the driven pulley 3 are not properly fitted. There is a risk that the V-ribbed belt 1 will fall off the driving pulley 2 and the driven pulley 3. On the other hand, if it exceeds 1.8 mm, the shape of the rib 13 becomes large and the torque cross increases. In addition, as for the distance (rib height i) from rib bottom part [4] to rib front-end | tip part [5], the range of 1.2-1.6 mm is more preferable.

(Compressed layer 12)
Examples of the rubber component of the rubber composition forming the compression layer 12 include vulcanizable or crosslinkable rubbers such as diene rubbers (natural rubber, isoprene rubber, butadiene rubber, chloroprene rubber, styrene / butadiene rubber (SBR), acrylonitrile). Butadiene rubber (nitrile rubber), hydrogenated nitrile rubber, etc.), ethylene-α-olefin elastomer, chlorosulfonated polyethylene rubber, alkylated chlorosulfonated polyethylene rubber, epichlorohydrin rubber, acrylic rubber, silicone rubber, urethane rubber, fluorine rubber Etc. can be exemplified. These rubber components may be used alone or in combination of two or more. Preferred rubber components are ethylene-α-olefin elastomers (ethylene-α-olefin rubbers such as ethylene-propylene rubber (EPR) and ethylene-propylene-diene monomers (EPDM, etc.)) and chloroprene rubber. A particularly preferable rubber component is an ethylene-α-olefin elastomer which is excellent in durability against chloroprene rubber and does not contain a halogen. Examples of the diene monomer of EPDM include dicyclopentadiene, methylene norbornene, ethylidene norbornene, 1,4-hexadiene, cyclooctadiene and the like.

  In particular, in view of heat resistance and wear resistance, EPDM which is a copolymer of ethylene, α-olefin and non-conjugated diene is preferable. Among them, ethylene content is 51 to 68% by mass, and double bond (Diene content) is preferably 0.2 to 7.5% by mass. As this EPDM, it is preferable to use one having an iodine value of 3 to 40. If the iodine value is less than 3, the rubber composition is not sufficiently vulcanized, and there is a possibility that problems of abrasion, adhesion, and pronunciation may occur. In addition, when the iodine value exceeds 40, the scorch of the rubber composition becomes short and difficult to handle, and the heat resistance may be deteriorated.

  The energy applied when the V-ribbed belt 1 bends generates internal heat of the compressed rib rubber (compressed layer 12) and causes torcross. In the rubber composition forming the compression layer 12, the content ratio of the ethylene-α-olefin elastomer in the rubber composition is set to 45% by mass or more, and the content ratio of carbon black is set to less than 35% by mass. The dynamic viscoelasticity tan δ (loss tangent) of the compression layer 12 formed by curing the rubber composition is decreased by increasing the content ratio of the ethylene-α-olefin elastomer and decreasing the content ratio of the carbon black. be able to. When the content ratio of the ethylene-α-olefin elastomer is 45% by mass or more and the content ratio of the carbon black is less than 35% by mass, the dynamic viscoelasticity of the compression layer formed using this rubber composition is reduced to the initial value. When measured under conditions of a strain of 1.0%, a frequency of 10 Hz, and a dynamic strain of 0.5%, the maximum value of tan δ in the range of 25 to 120 ° C. can be adjusted to less than 0.150. When the content ratio of the ethylene-α-olefin elastomer is less than 45% by mass or when the content ratio of carbon black is 35% by mass or more, tan δ becomes a large value of 0.150 or more, and the internal loss of the compressed rubber layer is Increases and increases torque cross.

  The upper limit of the content ratio of the ethylene-α-olefin elastomer in the rubber composition is not particularly set, but in practice, the content ratio of the ethylene-α-olefin elastomer is desirably 55% by mass or less. Further, the lower limit of the carbon black content ratio is not particularly set, but if the carbon black content ratio is less than 20% by mass, the wear resistance of the rubber composition is deteriorated and the durability of the V-ribbed belt 1 is reduced. Therefore, the content ratio of carbon black is preferably 20% by mass or more. Since the durability tends to decrease when the content ratio of carbon black is reduced in this way, it is preferable to use graphite together to reduce the content ratio of carbon black while suppressing the decrease in durability.

  Further, the rubber composition forming the compression layer 12 may further include a crosslinking agent such as an organic peroxide, N, N′-m-phenylene dimaleimide, and quinone dioxime, which are usually blended in the rubber as necessary. A co-crosslinking agent such as sulfur, a vulcanization accelerator, a filler such as calcium carbonate and talc, a plasticizer, a stabilizer, a processing aid, a colorant, and short fibers. Short fibers include cotton, polyester (PET, PEN, etc.), nylon (6 nylon, 66 nylon, 46 nylon, etc.), aramid (p-aramid, m-aramid), vinylon, polyparaphenylene benzobisoxazole (PBO) A fiber etc. can be used. These short fibers can be used alone or in combination of two or more. These various blends can be formed into a sheet by kneading them using commonly used means such as a Banbury mixer or a kneader.

(Rib 13)
As shown in FIG. 2, the compressed layer 12 has a plurality of ribs 13 extending in parallel with each other along the longitudinal direction M of the V-ribbed belt. And as shown in FIG. 4, the edge 13A of the front-end | tip part of this rib 13 is carrying out the square shape. Thus, since the edge 13A at the tip of the rib 13 has a square shape, the area where the rib 13 and the groove of the drive pulley 2 and the driven pulley 3 contact can be increased, and transmission performance can be maintained. it can.

  Generally, when the V-ribbed belt 1 is wound around the driving pulley 2 and the driven pulley 3 and the rib 13 is compressed and deformed, stress is concentrated on the edge 13A of the tip portion of the rib 13. In such stress concentration, if the rib height i is large, cracks are likely to occur from the tip of the rib 13. Therefore, as shown in FIG. 4, the conventional V-ribbed belt (for example, Japanese Translation of PCT International Publication No. 2007-509295) has a curved edge shape at the end of the rib in order to prevent the occurrence of cracks. However, since the V-ribbed belt 1 according to the present embodiment has a small rib height i, the V-ribbed belt 1 is formed with respect to the edge 13A of the tip portion of the rib 13 when the V-ribbed belt 1 is wound around the drive pulley 2 and the driven pulley 3. Since the stress can be made extremely small, the contour shape of the edge 13A at the tip of the rib 13 does not need to be a curved shape. In other words, the V-ribbed belt 1 according to the present embodiment has an edge 13A at the tip of the rib 13 having a square shape, so that the contour of the edge at the tip of the rib 13 is curved as in the prior art. Thus, the contact area between the rib 13 and the grooves of the drive pulley 2 and the driven pulley 3 can be increased.

(Extension layer 11)
As shown in FIG. 1, when the V-ribbed belt 1 is wound between the drive pulley 2 and the driven pulley 3, the back side of the V-ribbed belt 1 is stretched around the core wire 14. It is preferable that the stretch layer 11 forming the back side of 1 is composed of a rubber composition having a large stretch. The reason why the rubber composition is used for the stretch layer 11 as described above is that when the rubber composition is laminated (coated) or imprinted (friction) on a conventionally used canvas, compared to the rubber composition alone. Since the elongation is small, a greater force (tensile stress) is required to bend the belt and extend the stretch layer. If this tensile stress is high, the bending loss of the V-ribbed belt increases and the engine torque cross increases. It is.

  The elongation at break (corresponding to the circumferential direction of the V-ribbed belt 1) of the rubber composition forming the stretched layer 11 is preferably in the range of 110 to 240%. If the elongation at break is less than 110%, the tensile stress of the stretched layer 11 becomes high and the torque cross becomes large. On the other hand, if it exceeds 240%, the hardness of the stretched layer 11 is low, and in the case of driving the belt rear surface (the pulley is driven on the rear surface of the V-ribbed belt 1), the wear resistance decreases and adhesive wear occurs. The core wire 14 may be exposed due to the progress of wear. The elongation at break of the rubber composition forming the stretched layer 11 was measured by a rubber tensile test method in accordance with JIS K6251-1993. Specifically, a test piece obtained by punching a sheet of 150 × 150 × 2 mm thickness produced by press vulcanization molding of the rubber composition at 165 ° C. for 30 minutes into a dumbbell-shaped No. 5 It measured using the made strograph.

  The thickness of the stretch layer 11 (distance a from the center of the core [2] to the back surface of the V-ribbed belt [1]) is in the range of 0.6 to 1.5 mm, preferably in the range of 0.7 to 1.3 mm. More preferably, it is set in the range of 0.8 to 1.1 mm. If it is within this range, the tensile stress of the stretched layer 11 can be reduced to reduce the torque cross. If the thickness of the stretched layer 11 is less than 0.6 mm, the core wire 14 may be exposed due to progress of wear, or the stretched layer 11 may be cracked and the V-ribbed belt 1 may be cut (circular) in the circumferential direction. . On the other hand, if it exceeds 1.5 mm, the tensile stress of the stretched layer 11 becomes high and the torque cross increases.

  The rubber composition for forming the stretched layer 11 is preferably blended with the above-mentioned short fibers, and the shape thereof may be linear or partially bent (for example, milled fiber disclosed in JP-A-2007-120507). ). When a crack occurs in the circumferential direction M of the V-ribbed belt when the V-ribbed belt 1 travels, the V-ribbed belt 1 is prevented from being broken by orienting the short fibers in the V-ribbed belt width direction N or random direction. be able to. In addition, although the same rubber composition as the compression layer 12 mentioned above can be used for the rubber composition which forms the stretch layer 11, you may use a different rubber composition.

  By forming the stretch layer 11 with a rubber composition, it becomes easier to stretch than a conventionally used canvas, and the tensile stress of the stretch layer 11 when the V-ribbed belt 1 is wound around the drive pulley 2 and the driven pulley 3 is reduced. As a result, the bending loss of the V-ribbed belt 1 can be reduced and the torque cross can be reduced.

(Adhesive layer 15)
The adhesive layer 15 uses, as a rubber composition, a blend rubber obtained by mixing EPDM, which is a copolymer of ethylene, α-olefin, and non-conjugated diene, or a partner rubber made of other types of rubber. As the other rubber to be blended with EPDM, which is a copolymer of ethylene, α-olefin and non-conjugated diene, butadiene rubber (BR), styrene-butadiene rubber (SBR), nitrile rubber (NBR), hydrogenated nitrile rubber ( H-NBR), chloroprene rubber (CR), butyl rubber (IIR), and natural rubber (NR). As described above, the adhesive layer 15 is not essential, and is provided for the purpose of improving the adhesiveness of the core wire 14, the stretch layer 11, and the compression layer 12, and is bonded as in this embodiment. In addition to the configuration in which the core wire 14 is embedded between the layer 15 and the stretched layer 11, the core wire 14 may be embedded in the adhesive layer 15, and the core wire 14 is interposed between the compression layer 12 and the adhesive layer 15. The form to embed may be sufficient.

(Core 14)
The core wire 14 is not particularly limited. For example, polyester fibers such as polybutylene terephthalate (PBT) fibers, polyethylene terephthalate (PET) fibers, polytrimethylene terephthalate (PTT) fibers, polyethylene naphthalate (PEN) fibers, and 6 nylon fibers. Nylon fiber such as 66 nylon fiber, 46 nylon fiber, copolyparaphenylene 3,4'oxydiphenylene terephthalamide fiber, aramid fiber such as poly-p-phenylene terephthalamide fiber, polyarylate fiber, glass fiber, carbon A cord formed of fiber, PBO fiber, or the like can be used. These fibers can be used alone or in combination of two or more.

  The core 14 is preferably subjected to an adhesion treatment for the purpose of improving the adhesion with the stretch layer 11 and the compression layer 12. As such an adhesion treatment, the core wire 14 is immersed in a resin-based processing solution in which an epoxy or isocyanate is dissolved in an organic solvent, dried by heating, and then immersed in a processing solution such as a resorcin-formalin-latex solution (RFL solution). Then, it can be performed by heating and drying. If necessary, after the RFL treatment, an overcoating treatment may be performed with a treatment solution in which the rubber composition is dissolved in an organic solvent (toluene, xylene, methyl ethyl ketone, etc.).

  The diameter of the core wire 14 is preferably 1.25 mm or less. If it exceeds 1.25 mm, the bending stress of the core wire itself increases, and the engine torque cross increases, which is not preferable. The bending stress decreases as the diameter of the core wire 14 decreases, but considering the strength and modulus of the V-ribbed belt 1, the lower limit is approximately 0.6 mm.

(About the position of the core 14)
When the V-ribbed belt 1 is wound between the drive pulley 2 and the driven pulley 3, the core wire 14 is at the pulley side (at the V-ribbed belt 1) at a distance h from the rib bottom portion [4] to the core bottom portion [3]. In the core position A located on the compression layer 12 side and the core position B on the outer side, the torcross is reduced at the core position A (see FIG. 5). As shown in FIG. 5, when the V-ribbed belt 1 is wound around the pulley, if the position of the core wire 14 is on the pulley side, the thickness k of the compression layer 12 is reduced (the compression layer 12 of the core wire position A is This is because thickness k1 <thickness k2 of the compression layer 12 at the core position B), and the force (compression stress) required to bend the compression layer 12 is reduced. Moreover, since the winding length of the core wire 14 around the pulley is shorter in the core wire position A than in the core wire position B, the force (bending stress) required to bend the core wire 14 is reduced.

(Manufacturing method of V-ribbed belt 1)
Next, a method for manufacturing the V-ribbed belt 1 will be described.
First, a rubber composition for forming an extension layer, a rubber composition for forming a compression layer, and a rubber composition for forming an adhesive layer mixed with the materials described in the composition table of Table 1 are known methods such as a Banbury mixer. The kneaded rubber is kneaded with rubber, and the kneaded rubber is passed through a calender roll to produce a stretch layer forming sheet, a compressed layer forming sheet, and an adhesive layer forming sheet having a predetermined thickness.

  Next, the V-ribbed belt 1 is prepared using the following known method. First, a stretch layer forming sheet (unvulcanized rubber sheet) is wound around a cylindrical molding mold having a flat surface, and a core wire 14 is spun into a spiral shape on the stretch layer forming sheet (unvulcanized rubber sheet). A vulcanized rubber sheet) and a compressed layer forming sheet (unvulcanized rubber sheet) are sequentially wound to produce a molded body.

  After that, a vulcanization jacket is placed on the molded body and the mold is placed in a vulcanizing can. After vulcanization at a temperature of 160 ° C. for 30 minutes, the mold is removed from the molding mold and the cylindrical vulcanization is performed. A sulfur sleeve was obtained. Then, the outer surface of the vulcanized sleeve (corresponding to the compression layer 12) is polished with a grinding wheel to form a plurality of ribs 13, and then cut into individual belts with a cutter to finish the V-ribbed belt 1.

  The distance h from the core bottom [3] to the rib bottom [4] was adjusted by changing the thickness of the compression layer forming sheet. The distance a from the center of the cord [2] to the back surface of the V-ribbed belt [1] was adjusted by changing the thickness of the stretch layer forming sheet. The rib pitch e, which is the width of the rib 13 in the V-ribbed belt width direction N, was formed by adjusting the size (2.34, 3.56 mm) using two different grinding wheels. The rib height i is adjusted using two different grinding wheels (Examples 1 to 3 and Comparative Examples 1 to 3 to be described later), or after being polished into a rib shape using the grinding wheel, the rib 13 is The size was adjusted by flat polishing (Example 4 described later). The distance j from the rib tip [5] to the core bottom [3] was adjusted by changing the distance h from the core bottom [3] to the rib bottom [4] and the rib height i. The adhesive layer forming sheet had a constant thickness of 0.5 mm.

(Torcross measurement and transmission performance measurement)
The configuration of the V-ribbed belt 1 and the manufacturing method thereof have been described above. Next, a comparative experiment of the torque cross of the V-ribbed belt 1 and a comparative experiment of transmission performance will be described. In order to measure the dimensions of the V-ribbed belts according to the following examples and comparative examples, the V-ribbed belt was cut in a direction parallel to the V-ribbed belt width direction N, and the cut surface was scanned with a scanning electron microscope (manufactured by JEOL Ltd.). The size of each part of the V-ribbed belt is measured by magnifying using “JSM5900LV”).

(Dimensions of V-ribbed belts according to examples and comparative examples)
As shown in Table 2, the manufactured V-ribbed belt has 7 levels including Examples and Comparative Examples. In the V-ribbed belt according to Example 1, the distance a from the center of the core [2] to the back of the V-ribbed belt [1] is 0.80 mm, and the distance b from the bottom of the core [3] to the back of the V-ribbed belt [1] is 1. 20 mm, distance c from rib bottom [4] to V-ribbed belt back [1] is 2.30 mm, distance d from rib tip [5] to V-ribbed belt back [1] is 3.80 mm, rib pitch e is 2 .34 mm, V-ribbed belt width f is 18.72 mm, distance h from core bottom [3] to rib bottom [4] is 1.10 mm, distance i from rib tip [5] to rib bottom [4] Is 1.50 mm, and the distance j from the rib tip [5] to the core bottom [3] is 2.60 mm.

  In the V-ribbed belt according to Example 2, the distance a from the center of the core [2] to the back of the V-ribbed belt [1] is 1.30 mm, and the distance b from the bottom of the core [3] to the back of the V-ribbed belt [1] is 1. 90 mm, distance c from rib bottom [4] to V-ribbed belt back [1] is 2.30 mm, distance d from rib tip [5] to V-ribbed belt back [1] is 4.30 mm, rib pitch e is 3 .56 mm, V-ribbed belt width f is 21.36 mm, distance h from core bottom [3] to rib bottom [4] is 0.40 mm, distance i from rib tip [5] to rib bottom [4] Is 2.00 mm, and the distance j from the rib tip [5] to the core bottom [3] is 2.40 mm.

  In the V-ribbed belt according to Example 3, the distance a from the center of the core [2] to the back of the V-ribbed belt [1] is 1.10 mm, and the distance b from the bottom of the core [3] to the back of the V-ribbed belt [1] is 1. 50 mm, distance c from rib bottom [4] to V-ribbed belt back [1] is 2.30 mm, distance d from rib tip [5] to V-ribbed belt back [1] is 3.80 mm, rib pitch e is 2 34 mm, V-ribbed belt width f 18.72 mm, distance h from core bottom [3] to rib bottom [4] is 0.80 mm, distance i from rib tip [5] to rib bottom [4] Is 1.50 mm, and the distance j from the rib tip [5] to the core bottom [3] is 2.30 mm.

  In the V-ribbed belt according to Example 4, the distance a from the center of the core [2] to the back of the V-ribbed belt [1] is 0.80 mm, and the distance b from the bottom of the core [3] to the back of the V-ribbed belt [1] is 1. 20 mm, distance c from rib bottom [4] to V-ribbed belt back [1] is 2.30 mm, distance d from rib tip [5] to V-ribbed belt back [1] is 3.50 mm, rib pitch e is 2 .34 mm, V-ribbed belt width f is 18.72 mm, distance h from core bottom [3] to rib bottom [4] is 1.10 mm, distance i from rib tip [5] to rib bottom [4] Is 1.20 mm, and the distance j from the rib tip [5] to the core bottom [3] is 2.30 mm.

  In the V-ribbed belt according to Comparative Example 1, the distance a from the center of the core [2] to the back of the V-ribbed belt [1] is 1.00 mm, and the distance b from the bottom of the core [3] to the back of the V-ribbed belt [1] is 1. 60 mm, distance c from rib bottom [4] to V-ribbed belt back [1] is 2.30 mm, distance d from rib tip [5] to V-ribbed belt back [1] is 4.30 mm, rib pitch e is 3 .56 mm, V-ribbed belt width f is 21.36 mm, distance h from core bottom [3] to rib bottom [4] is 0.70 mm, distance i from rib tip [5] to rib bottom [4] Is 2.00 mm, and the distance j from the rib tip [5] to the core bottom [3] is 2.70 mm.

  In the V-ribbed belt according to Comparative Example 2, the distance a from the center of the core [2] to the back of the V-ribbed belt [1] is 1.00 mm, and the distance b from the bottom of the core [3] to the back of the V-ribbed belt [1] is 1. 60 mm, distance c from rib bottom [4] to V-ribbed belt back [1] is 2.80 mm, distance d from rib tip [5] to V-ribbed belt back [1] is 4.30 mm, rib pitch e is 2 34 mm, V-ribbed belt width f is 18.72 mm, distance h from core bottom [3] to rib bottom [4] is 1.20 mm, distance i from rib tip [5] to rib bottom [4] Is 1.50 mm, and the distance j from the rib tip [5] to the core bottom [3] is 2.70 mm.

  The V-ribbed belt according to Comparative Example 3 has the same configuration as the V-ribbed belt according to Comparative Example 1 except that the width f of the V-ribbed belt is 28.48 mm.

(Measuring method of Torcross)
Next, a method for measuring torque cross will be described. As shown in FIG. 6 (a), a V-ribbed belt is wound around a two-axis running test machine composed of a driving (Dr.) pulley having a diameter of 55 mm and a driven (Dn.) Pulley having a diameter of 55 mm, and 450 to 950 N / A predetermined initial tension was applied to the V-ribbed belt in the tension range of one belt, and the difference between the driving torque and the driven torque when the driving pulley was rotated at 2000 rpm with no driven pulley loaded was calculated as the torque cross. In addition, the torque cross calculated | required by this measurement contains the torque cross resulting from the bearing of a testing machine other than the torque cross by the bending loss of a V-ribbed belt. Therefore, a metal belt (material: maraging steel) considered to have a torque cross as a V-ribbed belt of substantially zero is run in advance, and the difference between the drive torque and the driven torque at this time is a torque cross due to the bearing (bearing loss). Therefore, a value obtained by subtracting the torque cross caused by the bearing from the torque cross calculated by running the V-ribbed belt (the torque cross resulting from the V-ribbed belt and the bearing) was obtained as the torque cross resulting from the single V-ribbed belt. Here, the torcross to be subtracted (bearing loss) is the torcross when the metal belt is run with a predetermined initial tension (for example, when the V-ribbed belt is run with an initial tension of 500 N / one belt, the metal belt is moved with this initial tension. (Torcross when running). The smaller the torque cross of this V-ribbed belt, the better the fuel economy.

(Torcross measurement results)
The relationship between the torque cross and the belt tension is shown in FIG. It can be seen that the V-ribbed belts of Examples 1 to 4 have a lower torque cross with respect to the belt tension than Comparative Examples 1 and 2, and are excellent in fuel efficiency. When Examples 1-4 were compared, Example 4 which made rib height i small was the lowest, and Example 2 where rib height i was the largest had the largest torque cross. Moreover, when Example 1 and Example 3 with the same rib height i are compared, the direction of Example 3 became smaller. This is because the distance j from the rib tip [5] to the core bottom [3] in Example 3 (the distance h from the cable bottom [3] to the rib bottom [4]) is 0. This is because it was 30 mm smaller.

(Measurement method of transmission performance)
Next, a method for measuring transmission performance will be described. As shown in FIG. 6B, a V-ribbed belt is wound around a two-axis running tester composed of a driving (Dr.) pulley having a diameter of 120 mm and a driven (Dn.) Pulley having a diameter of 120 mm, and an initial tension (329) is obtained. , 400, 526N / three levels of one belt) is applied to the V-ribbed belt, and then the load (driven torque) of the driven pulley is increased under the conditions of the drive pulley rotation speed of 2000 rpm and the room temperature atmosphere. The driven torque when the slip ratio reached 2% was measured. The higher the value of the driven torque, the better the transmission performance of the V-ribbed belt.

(Measurement result of transmission performance)
In order to investigate the influence of the rib height i on the transmission performance, the transmission performance was measured for the V-ribbed belts of Example 1 (1.50 mm) and Comparative Example 3 (2.00 mm) having different rib height i. The transmission performance depends on the rib height i and the number of ribs if the rubber composition of the compression layer 12 is the same. Therefore, Examples 1 and 3 and Comparative Example 2 can be considered to have similar transmission performance. The same applies to Example 2 and Comparative Example 1. The measurement results are shown in Table 3. The driven torque at 2% slip in Example 1 was slightly smaller than that in Comparative Example 3. This is because the V-ribbed belt width f is smaller in Example 1 than in Comparative Example 3. When this driven torque was converted per belt width of 1 cm and compared, the driven torque of Example 1 was higher than that of Comparative Example 3. This is because the rib pitch e is reduced to increase the number of ribs per unit width of the V-ribbed belt. Specifically, the number of ribs per 1 cm width (1 cm / rib pitch e) of the V-ribbed belt is 4.3 in Example 1 and 2.8 in Comparative Example 3. It can be seen that even if the rib height i is reduced, the transmission performance can be maintained by reducing the rib pitch e and increasing the number of ribs per unit width of the V-ribbed belt.

(Other embodiments)
Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above-described embodiments and examples, and various modifications can be made as long as they are described in the claims. It can be done.

  For example, the V-ribbed belt 21 shown in FIG. 8 is a rubber containing the stretched layer 11, the adhesive layer 15 disposed below the stretched layer 11, and the short fiber 16 disposed below the stretched layer 11, as in the above embodiment. And a compressed layer 12 formed of the composition. This V-ribbed belt 21 also has a rubber layer composed of three layers of an extension layer 11, an adhesive layer 15, and a compression layer 12, and the compression layer 12 constitutes an inner layer. Further, the core wire 14 is disposed so as to be embedded in the main body along the longitudinal direction M of the V-ribbed belt, and a part thereof is embedded in the stretched layer 11 and the remaining part is embedded in the adhesive layer 15. Is arranged in. The compressed layer 12 is provided with a plurality of ribs 13 having a substantially trapezoidal cross section in the V-ribbed belt width direction N and extending in the longitudinal direction M of the V-ribbed belt. And the short fiber 16 contained in the compression layer 12 of this V-ribbed belt 21 is contained in the state which orientated so that the flow state along the trapezoid shape of the rib 13 might be exhibited, as shown in FIG. In the vicinity of the surface 13, the short fibers 16 are contained in a state of being oriented along the outer shape of the ribs 13. As a method of forming the rib 13 in which the short fibers 16 are oriented as described above, there is a method of forming the rib 13 by press-fitting the compression layer 12 into a mold in which the rib 13 is engraved.

  Further, for example, the V-ribbed belt 31 shown in FIG. 9 includes a stretch layer 11 and a compressed layer 12 that is formed in a lower layer of the stretch layer 11 and is formed of a rubber composition that does not contain short fibers. Also good. In this V-ribbed belt 31, a rubber layer is constituted by two layers of an extension layer 11 and a compression layer 12, and the compression layer 12 constitutes an inner layer. Further, the core wire 14 is disposed so as to be embedded in the main body along the longitudinal direction M of the V-ribbed belt, and a part thereof is embedded in the stretch layer 11 and the remaining part is embedded in the compression layer 12. Is arranged in. The compressed layer 12 is provided with a plurality of ribs 13 having a substantially trapezoidal cross section in the width direction N of the V-ribbed belt and extending in the longitudinal direction M of the V-ribbed belt, and short fibers 32 are planted on the surface of each rib 13. ing.

1, 21, 31 V-ribbed belt 1A V-ribbed belt back 2 Drive pulley 3 Driven pulley 11 Stretch layer 12 Compression layer 13 Rib 13A Edge 14 Core wire 15 Adhesive layer 16, 32 Short fiber M V-ribbed belt longitudinal direction N V-ribbed belt width direction

Claims (3)

A V-ribbed belt used by being wound between pulleys,
A stretch layer forming the back surface of the V-ribbed belt;
A compression layer provided on one surface of the stretch layer and having a plurality of ribs extending in parallel with each other along the longitudinal direction of the V-ribbed belt;
A core wire embedded along the longitudinal direction of the V-ribbed belt between the stretch layer and the compression layer;
The width of the rib is 2.0 to 3.0 mm,
The distance from the bottom of the rib to the tip of the rib is 1.1 to 1.8 mm,
The distance from the outer peripheral portion of the core wire on the rib side to the tip end portion of the rib is 2.0 to 2.6 mm, and the distance from the outer peripheral portion of the core wire to the rib side to the bottom portion of the rib is 0 3 to 1.2 mm,
The stretch layer is formed of a rubber composition not containing canvas,
A V-ribbed belt, wherein a distance from the center of the core to the back of the V-ribbed belt is 0.6 to 1.5 mm. The rib has a width of 2.34 mm;
The distance from the outer peripheral part on the rib side of the core wire to the tip end part of the rib is 2.3 to 2.6 mm, and the distance from the outer peripheral part on the rib side of the core wire to the bottom part of the rib is 0 The V-ribbed belt according to claim 1, wherein the V-ribbed belt is 0.8 to 1.1 mm.   The V-ribbed belt according to claim 1 or 2, wherein a diameter of the core wire is 0.6 to 1.25 mm.